This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The long-term goal of this research is to understand the evolution and development of vertebrate morphological novelties. This research focuses on the developmental genetics of the invertebrate chordate amphioxus (Branchiostoma floridae). Amphioxus is generally considered the closest living relative of the vertebrates: both its body plan and genomic organization are vertebrate-like, but much simpler. Somites are a novel morphology found only in amphioxus and vertebrates. In vertebrates, they give rise to ribs, vertebrate, back muscles and dermis. The current work examines the conservation and changes in developmental gene expression patterns and the basic gene network required for somite development.